Maxillary second protraction with Case Report mini-implants and a By Neal D. Kravitz, DMD, MS transpalatal arch

hen you are protracting maxillary molars, molars, presence of all third molars, and acceptable condylar often anterior dental anchorage or Class III head shape bilaterally (Figure 3). directional elastics are sufficient to consolidate Study model analysis revealed a Class II division 1 subdi- Wspace without affecting position. However, in more vision right malocclusion, a tapered-maxillary arch, 40% over- challenging cases such as movement through a pneuma- bite, +4 mm of overjet, and moderate anterior crowding. tized sinus or molar substitution, skeletal anchorage may facilitate efficient molar protraction. This case report Treatment Objectives presents the treatment of an adolescent patient with early We identified five treatment objectives: loss of dysplastic maxillary first 1) establish functional Class I molars and successful, noncom- molar and canine pliant protraction of the second with normal overbite and molars using orthodontic mini- overjet; implants for anchorage. 2) resolve crowding; 3) develop a broader maxil- Diagnosis and Etiology lary-arch shape; A 13-year-old adolescent 4) align the dental midlines female was referred by her gen- with the facial midline; and eral dentist for an orthodon- 5) maintain soft-tissue esthetics. tic consultation following the recent extraction of severely Treatment Alternatives carious maxillary first molars. The patient presented to The patient presented with a Figure 1: Pretreatment composite. our office with the maxillary straight soft-tissue profile and first molars already extracted. good facial symmetry, with the Therefore, our treatment op- maxillary dental midline left tions were limited to either of the facial midline. Intraoral holding first-molar spaces for examination revealed miss- restorative treatment or molar ing maxillary first molars, full substitution (protracting the eruption of the maxillary sec- second molar into the first mo- ond molars, 180º malrotation of lar position). The maxillary left the maxillary left second pre- second would not be molar, forward position of the derotated to avoid prolonging maxillary right buccal segment treatment duration and risking due to the labially displaced pulpal necrosis. maxillary right canine, forward In regard to the first treat- position of the left mandibular ment option, the maxillary left buccal segment due to lingually Figure 2: Pretreatment cephalograph. second premolar would benefit displaced mandibular left later- from cuspal coverage; however, al incisor, and coinciding dental no other had car- midlines (Figure 1). ious lesions. Therefore, we did As shown in Figure 2, ce- not want to prepare bridgework phalometric analysis confirmed on healthy teeth. Furthermore, a mild Class II skeletal relation- the patient was approximately 4 ship (SNA: 79º; SNB: 76º). A years from skeletal maturity, and pretreatment panorex provided she was not interested in pursu- by her general dentist revealed ing endosseous dental implants. large carious lesions with pulpal Figure 3: Pretreatment panorex provide by general dentist. The second treatment op- involvement of the maxillary first Notice the dysplastic first molars (yellow circles). tion included protraction of the

18 OrthodonticProductsOnline.com February 2011 maxillary second molars into the first molar posi- tion. To aid molar protraction, we discussed incor- porating orthodontic mini-implants into the pal- ate. Due to the cost savings and the preservation of healthy teeth, this treatment option was chosen by the patient and supported by her referring dentist. Treatment Progress We fitted all teeth, excluding the maxillary first , with fixed, preadjusted edgewise appliances (Rocky Mountain Orthodontics Syn- ergy .018 slot in the anterior and Synergy-R .022 self-ligating slot in the posterior. We ligated .014 NiTi aligning archwires (also from RMO). At 2 months of treatment, we switched to .016 x .022 NiTi archwires for anterior torque and arch devel- opment (Figure 4). We placed two RMO Dual-Top mini-implants Figure 4: Treatment Montage. A) Upper and lower .014 NiTi wires after bond- ing. B) Upper and lower .016 x .022 NiTi wires. C) Upper and lower .017 x .025 (6-mm length and 1.6-mm diameter) in the para- stainless steel wires. Transpalatal arch has been placed and molar protraction median region of the maxillary palate, in line with has begun. D) Completion of molar protraction. the first premolars. We fitted bands on the max- illary first premolars for a pick-up impression to fabricate an AOA Laboratories transpalatal arch spanning premolar-to-premolar. I instructed the laboratory technician to keep the buccal brack- ets and solder palatal buttons on the bands. After fabrication, we cemented the transpalatal arch with GC Fuji LC, and we added RM Bond flow- able composite to secure the mini-implants to the transpalatal bar (Figure 5). After 4 months of treatment, we inserted .017 x 0.025 stainless steel archwires to begin consoli- dation. We placed buccal and palatal elastic chains (RMO Medium-Energy Chain) for efficient molar Figure 5: Treatment Montage, occlusal-view. A) Placement of 1.6- x 6.0-mm protraction. In less than 5 months (December 2007 mini-implants with a torsional-controlled contra-angled driver. Mini-implants to April 2008), we achieved complete space closure placed in the para-medium region. Two mini-implants were placed to stabilize with minimal tipping. the transpalatal arch. In critique, the mini-implants should have been placed After 9 months of treatment, we removed the farther apart for greater stability. Pick-up impression taken after placement of the mini-implants. B) We placed flowable composite to secure the transpalatal transpalatal arch and mini-implants, then bracketed arch to the mini-implants, and activated molar protraction with buccal and the maxillary first premolars. We then performed palatal elastic chains. C) Complete consolidation in less than 5 months. Notice final arch coordination and minimal occlusal equili- the small space opening distal to the right lateral incisor, indicating a slight loss bration. Once panoramic evidence confirmed mesial of anchorage even with the skeletal anchorage system. migration of the maxillary third molars into the sec- ond molar region, we bonded lingual retainers and took impressions for overlay Hawley retainers. At the debonding appointment, we gave the patient a refer- ral for extraction of the mandibular third molars. The total length of treatment was 16 months. Treatment Results The results of our treatment were an accept- able Class I relationship and a maintained facial balance (Figure 6). We obtained an appropriate incisal relationship by arch development, dis- tal uprighting of the maxillary , Figure 6: Final composite photographs. Notice the second molars fully pro- and labial advancement of the mandibular ante- tracted into a Class I occlusion. Also notice the lingual of the maxillary rior teeth with mild reproximation. Evaluation of left second premolar.

February 2011 OrthodonticProductsOnline.com 21 pretreatment and posttreatment ce- odontogenesis. Other environmental phalometric measurements showed factors may include birth-related trau- significant molar protraction, slight ma to the teeth and jaws, trauma dur- bite opening, and minimal changes ing intubation, poor prenatal and post- in lip position relative to the Esthetic natal nutrition (specifically, vitamin A Line (Figure 7). and D deficiency), hypoxia, infections, The 6-month posttreatment re- or exposure to toxic chemicals (such as cords showed good retention of the high dosages of fluoride, tetracycline, second molars and continued mesial and lead). Genetic factors include a eruption of the maxillary third molars variety of hereditary conditions such into the second molar position (Figure as trisomy 21, cerebral palsy, and meta- 8, page 24). bolic disorders.1 Treatment options of enamel dys- Discussion plasia depend on the severity of the le- Figure 7: Superimposition. Maxillary second Enamel Dysplasia, sometimes re- molars and mandibular first molars were traced. sion. Due to the nature of the dysplastic ferred to as (EH) or enamel, bonding is often challenging. simply dysplasia, is a defect that results in underdeveloped Conservative treatment may consist of stainless steel crowns, or malformed enamel. Dysplasia can occur on any or composite bonding, or with a full-coverage cast on multiple teeth, though it most commonly presents on the crown. In our patient, due to the large carious lesions with first molars or the central . The enamel defect may pulpal involvement, the general practitioner recommended present itself in a variety of forms, from a small pit-lesion extraction of the dysplastic first molars followed by protrac- to large orange-brownish mottling of the facial or occlusal tion of the second molars and spontaneous mesial drift of the surface of the tooth. Teeth with enamel dysplasia are often third molars. misshapen, hypersensitive, and may be more susceptible to The literature demonstrates that spontaneous third dental caries.1 molar drift following extraction of second molars is highly The cause of dysplasia may be multifactorial, but the predicable in the (96.2%) and less predictable in the defect is most commonly associated with infection or fe- (66.2%).2 During eruption, maxillary third molar ver during pregnancy or infancy that may interfere with crowns upright and maintain their angulation as they come

22 OrthodonticProductsOnline.com February 2011 into occlusion. Additional uprighting oc- treatment overbite, with or without the in- curs once molar occlusion is established.2 corporation of a transpalatal arch, would Factors that influence successful third- have provided sufficient dental anchorage molar eruption include initial angle of for molar protraction. While placement of eruption, jaw angulation, sex, age, and mini-implants ensured anchorage of the developmental stage of the third molar.3 transpalatal arch, the benefit of this case During the treatment of our patient, the report lies in sharing a method for molar maxillary second molars were protracted protraction that may be more applicable following extraction of the first molars. Figure 8: The final panorex reveals spon- when dental anchorage is insufficient. A post-treatment panoramic radiograph taneous mesial drift of the maxillary third revealed good erupting position and an- molars into the second molar position. The Conclusions gulation of the maxillary third molars. patient was referred for extraction of the Indirect skeletal anchorage with an mandibular third molars. To aid efficient molar protraction, anterior transpalatal arch can provide ef- we incorporated indirect skeletal anchorage using an ante- ficient, noncompliant maxillary molar protraction. The pro- rior transpalatal arch. Indirect skeletal anchorage is often traction of maxillary second molars after early loss of first preferable to direct anchorage when protracting posterior molars, and the subsequent mesial drift of the third molars, teeth for two reasons: allows for the reestablishment of Class I molar occlusion 1) greater biomechanical control, because forces are di- without costly posterior restorative treatment. OP rected along a continuous archwire; and 2) greater patient safety, because the mini-implant can Neal D. Kravitz, DMD, MS, is in private practice in South be placed in a variety of locations. Riding, Va, and White Plains, Md. He is a Diplomate The palate is a preferable location for indirect skeletal of the American Board of Orthodontics, and is on the anchorage due to its dense cortical bone, attached tissue faculty at the University of Maryland and Washington coverage, and low risk probability.4 Hospital Center. He would like to With this said, mini-implants were References for this article can thank the orthodontic residents at arguably not necessary to aid success- be found with the online version the University of Maryland for their ful molar protraction in this particular at OrthodonticProductsOnline.com. editorial guidance. He can be reached case. It is likely that the depth of pre- at [email protected].

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